SOLID STATE EMISSION: COPPER(I) HALIDE COMPLEXES WITH PHOSPHINE LIGANDS. By Elizabeth M. Holt, Paul B. Durand and Gilbert Mains, Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma 74078

Crystalline complexes of types; Cu₄X₄(PR₃)₄, Cu₂X₂(PR₃)₃ and CuX(PR₃)₂ have been observed to display cubic, rhombohedral and monomeric motifs, respectively, in which copper(I) displays three and four coordination. The stoichiometry of the complexes observed with various PR₃ ligands may be understood in terms of the cone angle subtended by the PR₃ group. When excited in the UV, these complexes may show emission in the visible range. For Cu₄X₄(PR₃)₄ complexes, a change from X=iodide to X=bromide leads to quenching of the visible emission. Those complexes (X=I) crystallizing with an internal three fold symmetry element emit in the 470-520 nm range whereas those with an internal two-fold axis emit at lower energy (575-615 nm) when excited at 300 nm. The presence of an aromadc ring in the phosphine ligand leads to quenching of the visible emission for complexes of the type: Cu₂X₂(PR₃)₃. Two allotropes of formula CuBr[P(cyclohexane)₃]₂ crystallize in different space groups depending upon the solvent. The form crystallized from hexane is found in space group C2/c with a 2-fold symmetry axis within the monomeric unit. When crystallized from benzene, space group P2₁/n is adopted and there is no internal symmetry element. The two forms display maximum emission at 460 and 400 nm. respectively. Packing differences are also noted. ab initio calculations lead to an understanding of the emission behavior of these complexes.